1. Field of the Invention
The present invention relates to an electro-optical device typified by an EL (electroluminescence) display device formed by fabricating semiconductor elements (elements using a semiconductor, typically transistors) on the surface of a substrate, and an electronic device (electronic equipment) including the electro-optical device as a display. Particularly, the invention relates to a method of manufacturing the same.
2. Description of the Related Art
In recent years, a technique for forming a thin film transistor (hereinafter referred to as a “TFT”) on a substrate has made remarkable progress, and its application and development to an active matrix type display device has proceeded. Especially, since a TFT using a polysilicon film has a field effect mobility higher than a conventional TFT using an amorphous silicon film, a high speed operation can be made. Thus, it becomes possible to control a pixel, which has been conventionally controlled by a driving circuit external to a substrate, by a driving circuit formed on the same substrate as the pixel.
Attention has been paid to such an active matrix type display device since various merits, such as reduction of manufacturing cost, miniaturization of a display device, increase of yield, and reduction of throughput, can be obtained by forming various circuits and elements on the same substrate.
In the active matrix type EL display device, a switching element made of a TFT is provided for each pixel, and a driving element for making current control is operated by the switching element, so that an EL layer (light emitting layer) is made to emit light. For example, there is an EL display device disclosed in U.S. Pat. No. 5,684,365 (see Japanese Patent Application Laid-open No. Hei 8-234683), or Japanese Patent Application Laid-open Publication No. Hei 10-189252.
As a method of forming the EL layer, various methods have been proposed. For example, there can be enumerated a vacuum evaporation method, sputtering method, spin coating method, roll coating method, cast method, LB method, ion plating method, dipping method, inkjet method, and the like.